Communication Error With Communication Processor; No Ack Signal; Continuous; Noise - Mitsubishi Electric PUZ-A18NHA4 Service Manual

Error Code Abnormal point and detection method
Communication error with communica-
tion processor
Defective communication between unit
processor and transmission processor
Note) The address and attribute display at
A6 remote controller indicate the con-
(6606) troller that detected abnormality.

NO ACK signal

1. Transmitting side controller detects
abnormal if a massage was transmitted
but there is no reply (ACK) that a mes-
sage was received. Transmitting side
detects abnormality every 30 seconds, 6
times continuously.
Note) The address and attribute displayed
at remote controller is indicate the
controller that did not reply (ACK).
A7
(6607)
2. If displayed address or attribute is out-
door unit, Indoor unit detects abnormality
when indoor unit transmitted to outdoor
unit and there was no reply (ACK).
3. If displayed address or attribute is indoor
unit, remote controller detects abnormal-
ity when remote controller transmitted to
indoor unit and there was no reply (ACK).
Case
1 Data of transmission proces-
sor or unit processor is not
transmitted normally because
of accidental trouble such as
noise or lightning surge.
2 Address forwarding from unit
processor is not transmitted
normally because of defective
transmission processor hard-
ware.
Common factor that has no rela-
tion with abnormality source.
1 The unit of former address
does not exist as address
switch has changed while the
unit was energized.
2 Extinction of transmission wire
voltage and signal is caused by
over-range transmission wire.
• Maximum distance ······ 200m
[656ft]
• Remote controller line .. (12m
[39ft])
3 Extinction of transmission wire
voltage and signal is caused by
type-unmatched transmission
wire.
Type······
With shield wire-
CVVS, CPEVS
With normal wire (no shield)-
VCTF, VCTFK, CVV
CVS, VVR, VVF, VCT
2
Diameter ····1.25mm [AWG16]
or more
4 Extinction of transmission wire
voltage and signal is caused
by over-numbered units.
5 Accidental malfunction of
abnormality-detected controller
(noise, lightning surge)
6 Defective of abnormality gen-
erated controller
1 Contact failure of transmission
wire of outdoor unit or indoor
unit
2 Disconnection of transmission
connector (CN2M) of outdoor
unit
3 Defective transmitting receiving
circuit of outdoor unit or indoor
unit
1 During group operation with
indoor unit of multi- refrigerant
system, if remote controller
transmit to indoor unit while
outdoor unit power supply
of one refrigerant system is
turned off or within 2 min-
utes of restart, abnormality is
detected.
2 Contact failure of transmission
wire of remote controller or
indoor unit
3 Disconnection of transmission
connector (CN2M) of indoor
unit
4 Defective transmitting receiving
circuit of indoor unit or remote
controller
43
Judgment and action
Turn off the power supply of outdoor unit and
indoor unit and FRESH MASTER or LOSSNAY
at the same time for 2 minutes or more, and
turn the power on again. System returns to
normal if abnormality was accidental malfunc-
tion. If the same abnormality generates again,
abnormality-generated controller may be defec-
tive.
Always try the followings when the error
"A7" occurs.
1 Turn off the power supply of outdoor unit
and indoor unit and FRESH MASTER or
LOSSNAY at the same time for 2 minutes or
more, and turn the power on again. If mal-
function was accidental, the unit returns to
normal.
2 Check address switch of abnormality gener-
ated address.
3 Check disconnection or looseness of abnor-
mality generated or abnormality detected
transmission wire (terminal block and con-
nector)
4 Check if tolerance range of transmission wire
is not exceeded.
5 Check if type of transmission wire is correct
or not.
If there were some troubles of 1-5 above,
repair the defective, then turn off the power
supply of outdoor unit and indoor unit and
FRESH MASTER or LOSSNAY at the same
time for 2 minutes or more, and turn the power
on again.
• If there was no trouble with 1-5 above in
single refrigerant system (one outdoor unit),
controller of displayed address or attribute is
defective.
• If there was no trouble with 1-5 above in dif-
ferent refrigerant system (2 or more outdoor
units), judge with 6.
6 If address of abnormality source is the
address that should not exist, there is the
unit that memorizes nonexistent address
information. Delete useless address informa-
tion with manual setting function of remote
controller.
Only the system FRESH MASTER or
LOSSNAY are connected to, or the system
that is equipped with group setting of differ-
ent refrigerant system.
If there was no trouble with 1-6 above, replace
the controller board of displayed address or
attribute.
If the unit does not return to normal, multi-con-
troller board of outdoor unit may be defective
(repeater circuit).
Replace multi-controller board one by one to
check if the unit returns to normal.
Continued to the next page.